The interactions between endogenous vasoactive peptides and target cells from the lung will be studied in vitro with cell cultures. The primary objective is to determine how these interactions may relate to tissue injury and inflammation. Cells derived from pulmonary blood vessels will be the major focus of these studies. Endothelial cells isolated from pulmonary arteries and veins will be distinguished from smooth muscle cells and fibroblasts by specific morphologic and biochemical markers. Since endothelial cells from human veins metabolize bradykinin, angiotensin and substance P, we will determine whether endothelial cells from human lung have similar activities. Enzymatic activity will be compared in cells from pulmonary arteries and veins to see if there is a differential distribution. Uptake of radiolabeled peptides by endothelial and smooth muscle cell will be studied to determine if they contain specific receptors for kinins, anaphylatoxins, or tissue-derived peptides such as substance P, VIP and VLP. Interaction with receptors will be correlated with stimulation of specific cell function such as formation of endoperoxides, or release of prostaglandins or surface-associated proteins (antigens, von Willebrand factor or enzymes). A related aspect of the project is the study of the effects of steroids and growth factors on the replication and enzyme activities of endothelial cells in culture. Stimulation of growth in culture will be correlated with enzymatic activities, and induction of enzyme activity will be examined.